Question

An aqueous solution of a substance gives a white precipitate on treatment with dilute hydrochloric acid, which dissolves on heating. When hydrogen sulphide is passed through the hot acidic solution, a black precipitate is obtained. The substance is a/an:

• A. $H{g}_2^{2+}$ salt
• B. $C{u}^{2+}$ salt
• C. $A{g}^{+}$ salt
• D. $P{b}^{2+}$ salt

Answer 1

Answer: (D)

$P{b}^{2+}$ salt

Option (D) is correct.
The substance is $P{b}^{2+}$ salt.
Lead is present in I and II group.
$\begin{array}{ccccccc}P{b}^{2+}& +& 2HCl& ⟶& PbC{l}_2\downarrow & \stackrel{H_{2}S}{\to }& PbS\downarrow \\ & & & & Whiteppt.& & Blackppt\\ & & & & dissolveson& & \\ & & & & boiling& & \end{array}$